1. Field of the Invention
This invention relates generally to internal pinion revolution counters and methods of assembling the same.
2. Description of the Prior Art
Mechanical revolution counters commonly comprise a plurality of successively higher order number wheels mounted on an input shaft, the revolutions of which are to be counted, the lowest order number wheel being connected to the input shaft and driven directly thereby. Intermittent motion transfer mechanism couples each number wheel to the next higher order number wheel, so that a predetermined number of revolutions of the lower order number wheel rotates the next higher order number wheel by a predetermined incremental amount. A common form of intermittent motion transfer mechanism comprises a segment of a gear rotating with the lower order number wheel, a locking cam which exposes a portion of the gear segment, and a transfer pinion assembly rotatably mounted on a pinion carrier. The transfer pinion includes a full tooth pinion rotated an incremental amount by the gear segment, a mutilated pinion section normally engaging the locking cam to inhibit rotation of the pinion other than at times when the full tooth pinion is rotated by the gear segment, and another full tooth pinion section meshing with the spur gear of the next higher order number wheel. In revolution counters of the internal pinion type, the transfer pinions are disposed within the peripheries of the number wheels.
U.S. Pat. No. 3,002,687 assigned to the assignee of the present application discloses an internal pinion counter wherein each number wheel and the spur gear, locking cam and gear segment associated therewith are retained in assembled relation by a pin, and each pinion carrier is a disc extending between a pair of number wheels and having a portion projecting outwardly from a respective pair of number wheels to be engaged by a portion of the frame of the counter.
There are applications for miniature internal pinion counters and in such miniature constructions, insufficient room is available for the retaining pins and the portion of the frame which engages the pinion carrier disc projections disclosed in the aforesaid U.S. Pat. No. 3,002,687. It is therefore desirable to provide an internal pinion counter construction and method of assembling the same which eliminates the assembly of the number wheels, spur gears, locking cams and gear segments by the use of pins, and the restraint of the pinion carrier discs by the frame, as disclosed in the aforesaid U.S. Pat. No. 3,002,687.